German Patent Publication (DE-OS) No. 3,236,109 discloses, e.g., a method and an apparatus for determining the orientation of a crystal, whereby use is made of the Laue backscatter diagram for displaying the so-called backscatter Roentgen rays which are used to irradiate a crystal. The Laue diagram is well known and does not require further elaboration. In the arrangement of the above publication the X-ray and the detector centerline are oriented at an acute angle relative to the surface of the crystal being tested. The detector output is processed by a computer to determine the angle of the main crystal axes.
The use of the Laue backscatter diagram of Roentgen rays has a disadvantage mainly because flaws in the interior of a test sample, such as a turbine component, cannot be detected. The known method discloses flaws only in the surface zone of the sample to a depth of just a few microns.